[HN Gopher] Groundbreaking arm amputation surgery makes a 'phant... ___________________________________________________________________ Groundbreaking arm amputation surgery makes a 'phantom' hand seem real Author : hhs Score : 129 points Date : 2021-09-18 14:55 UTC (8 hours ago) (HTM) web link (www.statnews.com) (TXT) w3m dump (www.statnews.com) | tyingq wrote: | This short video of a guy operating a motorized prosthetic foot | is really interesting: | | https://videos-fms.jwpsrv.com/0_6146535c_0xe8e28ca538bc35a69... | | And this article does a better job of explaining the surgery: | https://bionicsforeveryone.com/agonist-antagonist-myoneural-... | | I guess, in a nutshell, they attach a small amount of muscle to | the nerve that controls something that's going to be cut off. And | they anchor that muscle on both ends. So that contracting and | relaxing it provides a real-world force feedback loop. Really | clever. | hanoz wrote: | This reminds me of an experiment recounted in a great book | _Phantoms in the Brain_ , which I always wanted to try. | | The subject sits with a model nose placed some distance in front | of them on which someone taps and strokes in some non predictable | fashion. At the same time the subject's own nose is touched in | precisely the same pattern. Subjects apparently report an | overwhelming sensation that the model nose, some meters in front | of them, is thier own nose! | golemotron wrote: | With an article title like that, you have no idea what you are in | for. | amjaeger wrote: | https://www.science.org/doi/abs/10.1126/scirobotics.aan2971 | | This is one of the first papers describing the AMI surgery. | cududa wrote: | Caveat: not a neuroscientist, but have worked with many and been | involved in MRI and fMRI imaging for investigating HCI concepts/ | products and marketing. As well, when I was younger had | trigeminal neuralgia, considered the most painful disease | (explained below), and became fascinated with neuroscience. | | The approach of closing the loop on agonist/ antagonist feedback | in muscle fibers makes an enormous amount of sense and is | brilliant. | | Without the two "outbound requests" happening in a closed system | the brain is left to approximate the difference between the | slight signal shift. Even nanosecond differences in "send/ | receive" requests would be registered as pain. | | I had a neurological condition called trigeminal neuralgia where | the myelin wears down between the positive/ negative nerve | bundles in the trigeminal nerve and occasionally touch. | | The reason it's considered the most painful affliction is the | trigeminal nerve is where your whole body's pain, pressure, and | heat sensory nerves converge. So when the +/- touch, every fiber | of you feels like it's being stabbed, burned, and crushed at the | same time. About 90% of folks with it have have one occlusion in | the myelin and will feel excruciating pain in a localized are. I | had 9 full occlusions and 20+ partial. So lucky me, I got to | experience it through my whole body. | | Basically, when the +/- nerves touch, no part of your body is | receiving/ returning the expected "latency" for pain, pressure, | or heat, and perceives the differences of return times as nerves | (including those in agonist/ antagonist muscle) being split/ | damaged, thus a pain response. | | Totally makes sense that closing the proper agonist/ antagonist | fibers to create a proper feedback loop could eliminate the | unexpected diff on signal requests that trigger phantom pain. | | EDIT: Just to give yourself some real world examples.. Do | something like build a fence with your friends, all day. One | person operates the saw, one the hammer, so on and so fourth. | | At the end of the day using the same tool in repetition, hold | your tool, everyone applies blindfolds, then have an | "experimenter" touch the subjects forearm at different points. | They'll experience the touch at a different point than if they | weren't holding the tool. | | When you use something for a long time you integrate it into your | "body schema" - basically your brains map of yourself. | | My absolute favorite example of body schema extension are | experienced crane operators in docks. They can see a container on | a ship, need to place it on a massive pile they've been building | all day, and can no longer see in their line of vision where | they'll place it. But they can still do it without being able to | see where they're dropping it. | | All that's to say - your brain builds better and better models of | it's container (body) and environment by developing more and more | precise models of input/ output diff expectations and essentially | a "path prediction" algorithm. | | When the actual data is outside of parameter/ estimates get out | of whack, we experience things like pain where there's no harm. | But in an amputee, agonist/ antagonist muscle fibers are no | longer on the same circuit. The body adapts, and sends two | different "ping" requests to both channels. | | So I guess to simplify all that: When theres a micron of | difference in length in key paired muscle fibers (as is common in | amputations, injury, etc), the brain sends two signals, diffs the | return times and if they're out of wack with past lived | experience you get pain. | | While the amputee still doesn't have the "normal" limb length the | body is expecting, closing the loop provides the expected send/ | receive timing variance. | stavros wrote: | How did you cure your condition? | cududa wrote: | Was an experimental one, and actually need to get part of it | repaired soon which I'm not looking forward to. | | But basically, the trigeminal nerve bundle comes up from your | neck through your right jawbone, heads up around your mouth | and cheek bone to your ear and brain stem. | | Mine involved having a molar removed (I need a new false one | - this one got me 16 years but the new ones are billed as | lasting a life time) with laparoscopic surgery to move up | into the cavity, and insert small bits of poly-fibers between | the offending occlusions in the myelin. If they manage to get | all of the offending parts, the myelin degradation stops - | for most people. Some with atypical cases or a case brought | on by multiple sclerosis there's no cure. As it is, there's | no treatment for symptoms but my god for those without a | solution, assisted suicide is truly the only humane thing. | Buttons840 wrote: | > Outside of a brain scanner, the restoration of proprioception | can in some ways give patients the feeling of having a real foot. | One AMI amputee was hiking recently while wearing a standard | prosthesis and stepped into a creek. He later described having | the sensation of water flowing over his prosthetic foot even | though it had no way to perceive that. "He trusted or embodied | his prosthesis more than someone who doesn't have this phantom | sensation," said Carty. | | I read about an experiment where people were shown various black | and white drawings over random grayish backgrounds. They then had | to estimate the hue of the grayish background - which was | tricking because it only has slight amount of red, or blue, etc). | The results clearly shows that the black sketch which was | overlayed on the gray background skewered peoples perceptions of | the color of the background. People could not simply observe the | color of the background without their other knowledge skewing | their perception. | | Yet another example that we don't really get a "raw feed" from | out senses. What we perceive has already gone through a lot of | "post-processing" by our brain. | agumonkey wrote: | do you know research about proprioception instability ? | krisoft wrote: | Absolutely. This is one of the reason why it is really hard to | explain to laymans why robotic perception is hard. The | conversation usually goes: why can't you just make it do | "obviously good action" when "condition" happens? And since | "condition" is something they can just see it is hard to | convince them the robot doesn't have access to it in a clear | and unambigous maner. | GravitasFailure wrote: | Rodney Brooks talked about building an ant robot trying to | mimic the real thing. He said a real ant has hundreds of | thousands to millions of sensors while the robot his team | built had 150, and they only barely could handle that. The | data living things gather from their environment and the | processing used on it is absolutely mind boggling. | alisonkisk wrote: | A phone camera has millions of sensors... | wyldfire wrote: | > Yet another example that we don't really get a "raw feed" | from out senses. What we perceive has already gone through a | lot of "post-processing" by our brain. | | Looking forward to HDR and Image Stablization in Humanity 2.0 | coming in 102022. | adwn wrote: | > in 102022 | | Is this refering to the holocene calendar? [1] If yes, then I | think you meant "12022" - unless you're really pessimistic | about the timeline... | | [1] https://en.wikipedia.org/wiki/Holocene_calendar | GordonS wrote: | > I read about an experiment where people were shown various | black and white drawings over random grayish backgrounds. They | then had to estimate the hue of the grayish background - which | was tricking because it only has slight amount of red, or blue, | etc) | | I'm colour blind, and if a picture is in black and white, I | can't always tell. | | A long while back our CRT TV broke, and started displaying | everything without colour - I had no idea until my wife pointed | it out! It's like my mind just makes up what it doesn't see. | | Another example that I always use is grass: if you showed me a | cropped image of grass and I didn't know it was grass, I'll | tell you "I don't know what colour it is, but I think it's | either red, brown or green". But if you point to some grass, | I'll always say "it's green!". | Timpy wrote: | I'm curious about your experience, do you actually feel like | you are seeing green, or do you just know that green is the | correct answer? | | We had a bunch of different candies on the table at game | night and I gave my friend some M&Ms, he thought they came | from a bag of mint flavored M&Ms. He said, "wow I never tried | these before, they really taste like mint." We all did a | double take, he definitely did not eat mint M&Ms, I don't | really remember if we even had mint M&Ms at the table. I | believe him when he says he says he tasted mint though, like | his brain placeboed the mint into place. | GordonS wrote: | With the TV, I actually feel like I'm seeing colours, even | if I don't know exactly what they are. | | With the grass example, I'm actually not entirely sure! I | mean, I obviously know that green is the correct answer, | but that knowledge kind of makes me feel like I'm seeing | green. | | But colour blindness is kind of weird, because for any | given thing/colour it's never just "I don't know" - I can | narrow it down to a few options, and _usually_ one of them | is the correct one; like for a desaturated green, I might | think it 's grey, green or pink. | Deestan wrote: | I wonder if it is related to the gray/red strawberry | effect https://www.illusionsindex.org/i/grey-strawberries | jvanderbot wrote: | To control a large body with ample signal propegation delays, | the brain probably predicts a lot (Werner's "Cybernetics" -- | outdated but not wrong). Big bodies have bigger brains | partially for this reason. | einpoklum wrote: | This almost sounds like it's about the NVIDIA's trouble with the | ARM deal. | ouid wrote: | I have always felt that the reason that we can't run in dreams is | because the sensation of running is not something that we | remember well enough to model. We can verify that sensation, but | not recreate it. An enormous amount of computation is offloaded | to the world. | alisonkisk wrote: | More likely it's because your body is semi paralyzed in sleep, | so your dreaming brain notices that your legs aren't moving. | simion314 wrote: | My assumption why in my dreams running feels hard like your | legs are made of led is because of the paralysis we suffer when | dreaming. Like I want to run but some subconscious things is | signaling that your legs are blocked so I get this sensation.(I | had similar experience with attempting to open my eyes n dreams | and feeling that they are glued or hard to open/keep them open) | leksak wrote: | I run in dreams. Good and bad. One of my favourite dreams start | with me running, and it crescendos towards a feeling of | effortlessness. The ease of my stride becomes complete, rarely | and barely do I have to touch the ground to continue propelling | myself forward. The few times that I do have to make ground | contact it is as if my forefoot merely licks the ground and I | experience something akin to almost-flight. | | It is not as if I'm weightless as much as having an | unbelievably elastic Achilles tendon that allows me to bound | ahead, completely and utterly free. With nothing to impede me. | | In nightmares, if I have to run, I'm not as swift. | YeGoblynQueenne wrote: | Interesting. When I have one of those dreams I start running | on all fours. Which is weird because I could never run like | that in real life. Although I tried to repeat the movement | when I was in the sea, once, and it kiind of worked, in that | I could propel myself forward, except I had to be underwater. | | Now that I think of it, I've never had a dream where I can't | _swim_ and I dream of swimming very often. | leksak wrote: | Maybe you could learn. Animal locomotion is pretty big on | YouTube. | ddlutz wrote: | Interesting I run in my dreams quite often. I didn't know some | people couldn't. However in my dreams I can't really punch, all | punches feel like they have no "weight" to them if that makes | sense. | DoreenMichele wrote: | _Herr said the AMI patients have felt less pain in their residual | limbs, and their limbs don't atrophy, as is typical after a | standard amputation, resulting in a poor fit and pain when using | a prosthesis._ | | So this is a really significant step forward with immediate | important benefits. "Use it or lose it." Muscle function is | preserved so the stump isn't simply rotting. It still has muscle | function which is essential to preserving vitality. | | Coincidentally, I happened to trip across this House MD clip | about phantom pain recently: | https://www.youtube.com/watch?v=aIMa6G6EmC8 | | It reminded me of seeing this on HN: | | _The Mirror Man: Treating Phantom Limb Pain With a Simple | Technology_ | | https://news.ycombinator.com/item?id=8157932 ___________________________________________________________________ (page generated 2021-09-18 23:00 UTC)